In a servo control device employed in, for example, a machine tool, various control methods have been proposed in order to improve the precision of positioning control. FIG. 13 simply shows, in outline, an example configuration of a machine tool. As shown in FIG. 13, the machine tool is provided with a bed 1 and a table 2 disposed on the bed 1. The table 2 is provided so as to be movable on the bed 1 along an X-axis direction. At a gate-shaped column 3, a cross rail is disposed along a Y-axis direction. A carriage 5 provided with a ram 6 is engaged with the cross rail 4 and is provided so as to be movable along the Y-axis direction.
Movement in the X-axis direction of the table 2 is performed by a ball-screw drive mechanism. Movement in the Y-axis direction of the carriage 5 provided with the ram 6 is also performed by another ball-screw drive mechanism installed at the column 3.
With a relatively large machine tool, such as the one shown in FIG. 13, high-precision positioning control of the carriage 5 and velocity control of the table 2 are required; however, during machining, low-frequency vibrations occur at the column, etc. due to movement of the cross rail 4, the carriage 5, and the ram 6, and there is a problem in that the positioning control of the carriage 5 and the ram 6 cannot be performed accurately.
In order to solve such a problem, for example, it has been proposed to model a servo system or a machine system and to perform feedforward compensation using a transfer function having an inverse of that model (for example, see Patent Literature 1).